The present invention relates to containers for holding and storing bulk materials. More particularly, the present invention relates to air-breathable containers that facilitate communication from the container of moisture emitted from a load of bulk materials such as agriculture leaf products that require substantial air movement throughout the load held in the container for drying and long-term storage.
Large-volume containers are often used for holding, storing, and transporting bulk materials, such as powders, agriculture leaf and root crop products, metal castings, plastic resins, and many other materials. Generally, the containers provide sturdy walls for protecting the bulk materials from entry of pests and from container failure while allowing the containers to be handled by equipment such as fork lift trucks and platen trucks. The containers are also often stacked in warehouses.
Some containers also facilitate the drying and curing of the bulk materials. For example, some agriculture leaf products require significant air movement throughout a load of such products for drying or curing the products without formation of biological contamination such as mold or fungus growth that may occur in stagnant air conditions. These agriculture products include peanuts, fruits, grains, vegetables, and leaf products.
Often, leaf products particularly are held in containers made with wood-slats that are secured together with enwrapping metal bands. There are gaps between adjacent edges of the wood slats in the wall of the container. As the leaf products emit moisture and dry, the moisture communicates from the container through the gaps to the atmosphere. The escape of the moisture prevents mold from attacking the leaf products. These containers also allow for long-term storage of the leaf products. This enables the products to cure to useful raw material. The containers have sturdy walls which enable the containers to be stacked for storage in warehouses.
In addition, raw tobacco leaf products are generally processed with heat and steam. Typically packed at around 100 degrees F., the leaf products in the loaded container experience rising heat and giving off of steam for about the first 12 to 24 hours. Excessive heat rise may cause damage to leaf products, such as char or burning which destroys the value of the product. Generally, after the first day, the temperature typically decreases to ambient levels. However, the first 12 to 24 hours are important to the release of temperature and moisture, and containers for such leaf products must accommodate temperature rise and moisture communication.
Also because the total weight of a single loaded container may run as high as fifteen hundred (1500) pounds, the packing and shipping of bulk materials presents several unique problems. One problem is that such bulk materials are typically poured or thrown into the container and shipped loose so that the packed materials xe2x80x9cflowxe2x80x9d about the interior of the container. Materials of lesser densities may be pressed or compacted during filling of the container. After filling, the memory of the packed material exerts an outward force on the side walls of the pack. The side walls of the container must be sufficiently rigid in the horizontal plane to withstand internal movement or expansion of the materials and thereby must resist against bulging as a result of internal material flow.
Another problem is that the side walls of the container must also be sufficiently rigid to permit stacking of one container on top of another. The side walls must provide sufficient compression strength to prevent any deformation or collapse of the container when others are stacked upon it. Warehouse storage of containers with product often stacks containers 4 or 5 containers high. To meet stacking requirements, containers must withstand designed 4:1 loading. For example, 1200 pound loads in containers in a warehouse stack five high impose a load of 4800 pounds on the bottom container. As a safety factor, the containers must therefore accomodate four times the expected load, or 19,200 pounds of compression strength (generally tested at standard conditions of 73xc2x0 F. and 50% relative humidity).
In addition to the requirement that the container facilitate air and moisture communication, the container needs to restrict entry of pests into the walls of the container and into the load packaged therein, to reduce pest contamination and destruction of the product.
U.S. Pat. No. 4,635,815 describes a corrugated paperboard container having an exterior tubular corrugated paperboard body laminated to an interior tubular corrugated paperboard body, and includes of support members fixedly secured between the exterior and interior bodies so as to reinforce the container. While this container has been successful in long-term storage of bulk materials, it has not been gainfully used with fresh leaf products. The corrugated paperboard would prevent escape of moisture from the container. The leaf products would become damaged by mold and decay which leads to lost value. The leaf products must first dry by removal of the moisture held in the leaf products before long term storage can be made successfully with paperboard-type containers. However, transfer of such leaf products from the wood slat containers to the corrugated paperboard container after drying is not efficient. The wood slat containers have drawbacks to their continued use for leaf products. These problems include the costs and availability of such containers.
U.S. Pat. No. 6,126,067 describes a corrugated paperboard container having at least one side panel with a plurality of openings defined by drilling through the side panel with a non-fluted drill, whereby the openings provide for communicating moisture through the panel and outwardly of the container. While this container satisfactorily facilitates drying of leaf products, some believe there are drawbacks which may limit the use of such containers. Particularly, the open flutes in the corrugated side panel may become occluded such as with dust particles carried by the communicated air, and the effectiveness of the container for drying leaf products may be reduced.
Co-pending U.S. patent application Ser. No. 09/994,176 describes a corrugated paperboard container having at least one side panel with a plurality of openings defined by punching through the side panel with a tapered pin, whereby the openings provide for communicating moisture through the panel and outwardly of the container while a portion of the outer paperboard sheet at least partially covers the flutes in the opening as it is formed. While this container satisfactorily facilitates drying of leaf products, some believe there are drawbacks which may limit the use of such containers. Particularly, the open flutes in the corrugated side panel may not be uniformly closed, and the opening may become occluded such as with dust particles carried by the communicated air, thereby reducing the effectiveness of the container for drying leaf products.
Accordingly, there is a need in the art for an improved air-breathable container that facilitates communication from the container of moisture emitted from the leaf products held in the container for drying and long-term storage. It is to such that the present invention is directed.
The present invention solves the above-described problems in the prior art by providing a container that facilitates communication of moisture from the container for drying and long-term storage of leaf products. The container comprises a blank of a corrugated paperboard sheet having a flute sheet interposed between opposing paperboard sheets and scored to define two opposing end panels and two opposing side panels. The blank is foldable on the scores and a pair of opposing distal ends are adhered together to define a tubular body openable from a first position which is substantially flat to a second position squared-open for receiving a plurality of leaf products within a cavity defined by the opposing end and side panels. At least one of the panels defines a plurality of spaced-apart passageways for communicating moisture through the panel. The panel defines a compressed portion about a perimeter of each of the passageways, which portion is substantially compressed relative to a thickness of the panel, whereby the flutes of the panel are significantly closed. An air permeable sheet attaches to the panel in overlapping relation to each of the passageways. A bottom closes a first open end of the tubular body and a top cap closes a second open end of the tubular body. The leaf products, being held within the tubular body, emit moisture which communicates through air permeable sheet on the panel to atmosphere for drying and long-term storage of the leaf products.
In another aspect, the present invention provides an air-permeable container having an outer wall-forming blank of corrugated paperboard scored to provide a series of main panels foldably joined together and a second wall-forming blank of corrugated paperboard also scored to provide a series of main panels foldably joined together. The second wall-forming blank bonds to the inside surface of the first wall-forming blank. A plurality of support members are fixedly retained about a perimeter of each main panel between the first wall-forming blank and the second wall-forming blank. At least one of the main panels in the first and second wall-forming blanks define a plurality of spaced-apart passageways. A plurality of air permeable sheets attach to the second wall-forming blank in overlying relation to the passageways. The unitary container accordingly facilitates communication of moisture from leaf products through the air permeable sheets to atmosphere while the reinforced side walls provide compression strength and prevent against any bulging.
In another aspect, the present invention provides a container for drying and long-term storage of leaf products made by the process comprising the steps of:
(a) providing a blank of a sheet material scored to define two opposing end panels and two opposing side panels;
(b) pressing a die against the sheet material, the die having at least one cutter to define a passageway therethrough and the die further including a resilient body around a perimeter of the cutter and extending from the die substantially as far as the cutter, whereby a portion of the sheet material about the passageway is substantially compressed thereby while the passageway is cut therein by passage of the die against the sheet material;
(c) attaching an air permeable patch to the sheet material overlying each one of the passageways;
(d) folding the blank on the scores;
(e) adhering a pair of opposing distal ends of the blank adhered together to define a tubular body openable from a first position which is substantially flat to a second position squared-open for receiving a plurality of leaf products within a cavity defined by the opposing end and side panels; and
(f) providing a bottom and a top cap that close opposing open ends of the tubular body,
whereby leaf products, being held within the tubular body, emit moisture which communicates through the air permeable patches covering the passageways in the panel to atmosphere for drying and long-term storage of the leaf products.
Objects, advantages and features of the present invention will become apparent from a reading of the following detailed description of the invention and claims in view of the appended drawings.